JP2006057796A - Pressure vessel and hydraulic accumulator/shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint having a sufficient welding part strength by obtaining a large welding load and a uniform contact in resistance welding. <P>SOLUTION: The pressure vessel is characterized by the feature that the pressure vessel is provided with a steel pipe 40 and an end plate 50 by forming and blanking the joint Q while abutting the taper surface 51d to a taper surface 41c of the opening end of the steel pipe 40 and the steel pipe 40 has a flange portion 45 which can be cut in the opening end side, and the joint Q presses the flange portion 45 along the axial direction C to the opening end side, while being abutted by the flange portion 45, and the joint Q presses the end plate 50 along the axial direction C to the steel pipe 40 side, while being abutted by the end plate 50, and the joint Q is welded and formed by passing an electric current. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pressure vessel such as an accumulator and an accumulator / buffer device used in automobiles and industrial machines, and more particularly to a uniform welded portion between a mirror plate and a body portion. The present invention relates to a technique for improving the efficiency of manufacturing processes and reducing costs.

  Accumulators (accumulation and shock absorbers) are used in hydraulic circuits and shock absorbers of hydraulic control devices. The accumulator is generally configured such that the inside of the pressure vessel is partitioned into a gas chamber and an oil chamber by a bellows, and the pressure fluctuation of the oil flowing into the oil chamber is buffered by the expansion and contraction action of the gas in the gas chamber accompanying the expansion and contraction of the bellows. (For example, see Patent Documents 1 to 3). An accumulator is widely used in, for example, automobiles and industrial machines as a device for effectively suppressing pulsation generated in oil flowing in a hydraulic circuit.

  In order to form the pressure vessel, it is necessary to join the outer shell member and the lid for closing the member with high strength. For example, resistance welding can be used in a thin pressure vessel (thickness of 2 mm or less). 4 and 5 are views showing an example of such a pressure vessel. That is, the pressure vessel 10 includes a steel pipe (outer shell member) 11 and an end plate 12 that covers the opening of the steel pipe 11. In FIG. 4, reference numerals 13 and 14 denote electrodes.

  When resistance welding is performed, the outer surface of the steel pipe 11 is clamped with the split electrode 13, the outer surface of the end plate 12 is inserted into contact with the inner wall surface from the end side of the steel pipe 11, and the outer surface of the steel pipe 11 is inserted. The electrode 14 is brought into contact with. On the other hand, the electrode 14 is brought into contact with the upper surface of the end plate 12. While applying a load between the electrodes 13 and 14, current was passed through the electrode 13, the steel pipe 11, the end plate 12, and the electrode 14, and the inner wall surface of the steel tube 11 and the outer side surface of the end plate 12 were resistance welded.

On the other hand, in the thick pressure vessel (thickness of 2 mm or more) as shown in FIG. 6, joining was performed by outer peripheral surface CO ₂ welding, TIG welding, or the like (see F in FIG. 6). FIG. 6 is a diagram showing an example of an accumulator. That is, the accumulator 20 includes a cylindrical shell (outer shell member) 21, a first end plate (lid body) 22 fitted into one opening of the shell 21, and a second fitted into the other opening. End plate (lid body) 23 is provided. A through hole 22a is formed in the first end plate 22 and is hermetically closed by a gas sealing plug 22b. A port 23a is formed in the second end plate 23, and is connected to a hydraulic circuit or the like so that oil can freely enter and exit.

A disc-shaped bellows cap 25 is slidably provided along the axial direction of the shell 21 via a metal bellows 24 on the lower surface of the first end plate 22 in FIG. 6 denotes a guide attached to the outer peripheral portion of the bellows cap 25. The guide 26 has a function of assisting the sliding of the bellows cap 25. A space formed by the first end plate 22, the metal bellows 24, and the bellows cap 25 is a gas chamber G in which nitrogen gas or the like is enclosed. An oil chamber L is formed between the second end plate 23 and the bellows cap 25.
JP 2001-116002 A JP 2001-116003 A JP 2003-120601 A

The above-described pressure vessel joining method has the following problems. That is, in resistance welding, since the steel pipe is gripped by the split electrode, uniform contact and a large clamping force cannot be obtained, and it can be used only for thin steel pipes having a thickness of up to about 2 mm. Further, in the case of a thick-walled steel pipe, there has been a problem that it becomes large and heavy in order to obtain the welded portion strength by performing the outer peripheral surface CO ₂ welding, TIG welding or the like.

  Accordingly, the present invention provides resistance welding while applying a large load (hereinafter referred to as “welding load”) necessary for resistance welding to pass a large welding current (for example, 300 kA or more) necessary to use a thick member. Therefore, it is possible to obtain a uniform contact surface pressure during welding, to form a joint having sufficient weld strength, and to discharge the member at this portion without having to split the electrode into two parts. Therefore, an object of the present invention is to provide a pressure vessel and a pressure accumulating / buffering device in which the surface of the member is not roughened.

  In order to solve the above problems and achieve the object, the pressure vessel and the pressure accumulating / buffer device of the present invention are configured as follows.

(1) A cylindrical outer shell member, and a lid that closes the inner wall portion of the open end of the outer shell member by abutting the side wall portion to form a joint and closing the outer shell member, A flange portion that can be cut off at the opening end side, and the joint portion is brought into contact with the flange portion, and the flange portion is pressed toward the opening end side along the axial direction. It is formed by being welded by applying an electric current while abutting and pressing the lid body toward the outer shell member along the axial direction.

(2) The pressure vessel according to (1), wherein the flange portion is cut out after the joint portion is formed.

(3) a pressure vessel, and a gas chamber provided in the pressure vessel and capable of enclosing gas and a liquid chamber capable of flowing in and out of the liquid, the pressure vessel including a cylindrical outer shell member, And a lid that closes the inner wall of the open end of the shell member by abutting the side wall to form a joint, and the outer shell has a removable flange on the open end. The joint portion is brought into contact with the flange portion, and the flange portion is pressed toward the opening end side along the axial direction so as to come into contact with the lid body, and the lid body is brought into contact with the shaft. It is formed by being welded by applying an electric current while pressing toward the outer shell member along the direction.

(4) The pressure accumulating / buffering device according to (3), wherein the air chamber and the liquid chamber are partitioned by a metal bellows formed to be stretchable along the inner wall surface of the pressure vessel. The pressure accumulating / buffer device according to claim 3.

(5) The pressure accumulating / buffering device described in (4) above, wherein one open end of the metal bellows and the lid are hermetically welded.

(6) The pressure accumulating / buffering device according to (5), wherein a cylindrical body is attached coaxially to the outer shell member on the inner surface side of the end plate,
The other opening end of the metal bellows is covered with a bellows cap, and the bellows cap is attached with a sealing functional member that comes into contact with the cylindrical body when the metal bellows contracts,
The lid is provided with a port that allows liquid to flow in and out of the outside,
6. The pressure accumulating / buffering device according to claim 5, wherein a space surrounded by the lid, the bellows cap, and the metal bellows is a liquid chamber.

  According to the present invention, even when a large welding current is applied using a thick member, a joint having sufficient weld strength is formed by obtaining a large welding load and uniform contact in resistance welding. It becomes possible to do.

  FIG. 1 is a longitudinal sectional view showing an accumulator (accumulation / buffer device) 30 according to an embodiment of the present invention, and FIG. 2 schematically shows a joint Q between a steel pipe 40 and an end plate 50 incorporated in the accumulator 30. It is a longitudinal cross-sectional view. In FIG. 1, G indicates a gas chamber (air chamber), and L indicates an oil chamber (liquid chamber).

  The accumulator 30 includes a bottomed cylindrical steel pipe (outer shell member) 40, an end plate (lid body) 50 fitted in the opening of the steel pipe 40, and a bellows mechanism 60 accommodated in the steel pipe 40. . In addition, the pressure vessel is comprised by the steel pipe 40 and the end plate 50, The taper surface 41c mentioned later of the steel pipe 40 and the taper surface 51d mentioned later of the end plate 50 are joined by resistance welding, and the junction part Q is formed.

  The steel pipe 40 is formed by integrally connecting a pipe part 41 and a bottom part 42. A through hole 42 a is formed in the bottom 42. The through hole 42 a is airtightly closed by a gas sealing plug 43. Further, a cover 44 is attached to the outside of the through hole 42a. In FIG. 1, 41a indicates an inner wall surface of the pipe portion 41, 41b indicates an outer wall surface, and 41c indicates a tapered surface formed on the inner wall surface 41a side. Moreover, the two-dot chain line 45 in FIG. 1 has shown the flange part which can be cut off.

  The end plate 50 includes a end plate main body 51 formed in a disc shape, a port portion 52 provided in a central portion of the end plate main body 51 and having a through hole therein, and a cylindrical member joined to an upper surface 51a (described later) of the end plate main body 51. (Cylinder) 53.

  The end plate body 51 is arranged so that the upper surface 51 a side is the inside of the steel pipe 40 and the lower surface 51 b side is the outside of the steel pipe 40. A tapered surface 51d is formed from the side surface 51c to the upper surface 51a side. A ring-shaped part 54 made of rubber or resin is provided on the taper surface 51d to prevent spatter from entering the gas chamber G during welding.

  The bellows mechanism 60 is attached to a cylindrical metal bellows 61, a disk-shaped bellows cap 62 attached to one open end of the metal bellows 61, and a central recess 62a of the bellows cap 62. A sealing functional member 63 made of a rubber material and a guide 64 attached to the outer peripheral portion 62b of the bellows cap 62 are provided. Further, since the guide 64 slides on the inner peripheral surface of the pipe portion 41, the bellows cap 62 can move smoothly.

  The other open end of the metal bellows 61 is airtightly attached to the upper surface 51a of the end plate body 51 described above. The seal function member 63 is disposed so that the lower surface 63a thereof contacts the upper surface 53a of the cylindrical member 53 described above in a state where the metal bellows 61 is most contracted.

  In the accumulator 30 configured as described above, when the pressure of the pressure oil introduced into the oil chamber L through the through hole 52a of the port portion 52 exceeds the gas pressure of the gas chamber G, the metal bellows 61 expands. As a result, the gas in the gas chamber G contracts. On the other hand, when the pressure of the pressure oil in the oil chamber L falls below the gas pressure in the gas chamber G, the metal bellows 61 contracts and the gas in the gas chamber G expands. By such expansion and contraction of the gas in the gas chamber G, pressure fluctuations of the pressure oil in the hydraulic circuit are buffered, and pulsation of the pressure oil is suppressed.

  Next, the manufacturing process of the accumulator 30 will be described. First, the cylindrical member 53 is welded to the upper surface 51 a of the end plate body 51. After the metal bellows 61 and the bellows cap 62 are welded, they are welded to the upper surface 51 a of the end plate body 51.

  Next, as shown in FIGS. 2 and 3, resistance welding is performed between the end plate body 51 and the pipe portion 41. That is, the tapered surface 41 c of the tube portion 41 and the tapered surface 51 d of the end plate body 51 are abutted against each other. Next, the first electrode 70 of the resistance welder (not shown) is pressed against the lower surface 51b of the end plate main body 51 in the direction of arrow D in FIG. 2, and the second electrode 71 is pressed against the flange portion 45 of the tube portion 41 in FIG. Press in the U direction. The second electrode 71 is preferably ring-shaped. By using the ring-shaped electrode, unnecessary discharge to the flange portion 45 can be prevented. That is, the taper surface 41c and the taper surface 51d are pressurized. And it supplies with electricity between the 1st electrode 70 and the 2nd electrode 71, and resistance welding is performed. Thereby, the taper surface 41c and the taper surface 51d are melted and welded, and the joint portion Q is formed. In addition, the flange part 45 is excised as needed.

  In addition, when performing resistance welding, you may make it prevent the penetration | invasion of a foreign material by attaching the foreign material penetration | invasion prevention cap K to the port part 52. FIG.

  Resistance welding can be performed satisfactorily by applying a large welding load. Therefore, the steel pipe 40 and the end plate 50 are joined well, and the sealed state as the pressure vessel is surely and strong.

  As described above, according to the accumulator 30 according to the present embodiment, even when, for example, a steel pipe having a thickness of 2 mm or more and an end plate are joined using a resistance welding by applying a large welding current, the flange portion Since a uniform contact can be obtained by applying a large welding load via 45, a pressure vessel having sufficient weld strength can be formed.

  The present invention is not limited to the above embodiment. For example, in the above-described example, the pressure vessel for the accumulator has been described, but the present invention can also be applied to a pressure vessel used for applications such as a gas spring and a gas stay. Further, although the description has been given of the case where the end plate is provided only on one side, it is needless to say that the same can be applied to the case where the end plate is provided at both ends. Of course, various modifications can be made without departing from the scope of the present invention.

1 is a longitudinal sectional view showing an accumulator according to an embodiment of the present invention. The longitudinal cross-sectional view which shows typically the junction part of the steel pipe and end plate in the same accumulator. The longitudinal cross-sectional view which shows typically the junction part of the steel pipe and end plate in the same accumulator. The longitudinal cross-sectional view which shows an example of the joining method of the shell member and cover body in the pressure vessel used for the conventional accumulator. The longitudinal cross-sectional view which shows the same pressure vessel. The longitudinal cross-sectional view which shows the conventional accumulator.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 30 ... Accumulator, 40 ... Steel pipe (outer shell member), 41a ... Inner wall surface, 41c ... Tapered surface, 45 ... Flange part, 50 ... End plate (lid body), 51 ... End plate body, 51d ... Tapered surface, 54 ... Seal ring 60 ... Bellows mechanism, 61 ... Metal bellows, 62 ... Bellows cap, Q ... Joint part.

Claims (6)

A cylindrical outer shell member;
A lid that closes the side wall by contacting the inner wall of the open end of the outer shell member to form a joint,
The outer shell member has a flange portion that can be cut off on the opening end side,
The joint portion is in contact with the flange portion, presses the flange portion toward the opening end side along the axial direction, contacts the lid body, and the lid body in the axial direction. A pressure vessel formed by being welded by applying an electric current while pressing it toward the outer shell member side.   The pressure vessel according to claim 1, wherein the flange portion is cut out after the joint portion is formed. A pressure vessel;
Provided in this pressure vessel, comprising a gas chamber capable of enclosing gas and a liquid chamber capable of flowing in and out of the liquid,
The pressure vessel includes a cylindrical outer shell member,
A lid that closes the side wall by contacting the inner wall of the open end of the outer shell member to form a joint,
The outer shell member has a removable flange portion on the opening end side thereof,
The joint portion is in contact with the flange portion, presses the flange portion toward the opening end side along the axial direction, contacts the lid body, and the lid body in the axial direction. The pressure accumulating / buffering device is formed by being welded by applying an electric current while being pressed along the outer shell member side.   4. The pressure accumulating / buffering device according to claim 3, wherein the gas chamber and the liquid chamber are partitioned by a metal bellows formed to be stretchable along the inner wall surface of the pressure vessel.   An accumulator / buffer device, wherein one open end of the metal bellows and the lid are hermetically welded. A cylindrical body is attached coaxially with the outer shell member on the inner surface side of the end plate,
The other opening end of the metal bellows is covered with a bellows cap, and the bellows cap is attached with a sealing functional member that comes into contact with the cylindrical body when the metal bellows contracts,
The lid is provided with a port that allows liquid to flow in and out of the outside,
6. The pressure accumulating / buffering device according to claim 5, wherein a space surrounded by the lid, the bellows cap, and the metal bellows is a liquid chamber.

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